Light emitting device and method of manufacturing the same

ABSTRACT

A light emitting device is provided in which reduction of recombinations in a light emitting element is prevented by using a low-resistant electrode structure. A light emitting device of the present invention has a light emitting element composed of first and second electrodes and an organic compound layer that is sandwiched between the first and second electrodes, and the device is characterized in that one of the first and second electrodes has a transparent conductive film, a transparent conductive resin formed on the transparent conductive film, and a plurality of conductors formed on the transparent conductive resin.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a light emitting device with a lightemitting element that has a film containing an organic compound thatemits fluorescent light or phosphorescent light upon application ofelectric field (the film is hereinafter referred to as organic compoundlayer), and to a method of manufacturing the light emitting device.

In the present invention, a light emitting element is an element thathas an organic compound layer between a pair of electrodes and the termlight emitting device includes an image display device which uses thisorganic light emitting element. Also, the following modules are allincluded in the definition of the light emitting device: a moduleobtained by attaching to a light emitting element a connector such as ananisotropic conductive film (FPC: flexible printed circuit), a TAB (tapeautomated bonding) tape, or a TCP (tape carrier package); a module inwhich a printed wiring board is provided at an end of the TAB tape orthe TCP; and a module in which an IC (integrated circuit) is directlymounted to a light emitting element by the COG (chip on glass) method.

2. Description of the Related Art

Light emitting devices, which are characterized by their thinness andlight-weight, fast response, and direct current low voltage driving, areexpected to develop into next-generation flat panel displays. Amonglight emitting devices, ones having light emitting elements arranged toform a matrix are considered to be particularly superior to conventionalliquid crystal display devices for their wide viewing angle andexcellent visibility.

It is said that light emitting elements emit light through the followingmechanism: a voltage is applied between a pair of electrodes thatsandwich an organic compound layer, electrons injected from the cathodeand holes injected from the anode are re-combined at the luminescentcenter of the organic compound layer to form molecular excitons, and themolecular excitons return to the base state while releasing energy tocause the light emitting element to emit light. Excitation stateincludes a singlet exiton and a triplet exiton, and it is consideredthat luminescence can be made through either excitation state.

Light emitting devices having light emitting elements arranged to form amatrix can employ passive matrix driving (simple matrix light emittingdevices), active matrix driving (active matrix light emitting devices),or other driving methods. If the pixel density is large, active matrixlight emitting devices in which each pixel has a switch are consideredto be advantageous because they can be driven with low voltage.

In an active matrix light emitting device, a thin film transistor(hereinafter referred to as TFT) is formed on an insulating surface, aninterlayer insulating film is formed over the TFT, and an anode of thelight emitting element is formed to bc electrically connected to the TFTthrough the interlayer insulating film. The material suitable for theanode is a transparent conductive material having a large work function,typically, ITO (indium tin oxide).

An organic compound layer is formed on the anode. The organic compoundlayer includes a hole injection layer, a hole transporting layer, alight emitting layer, a blocking layer, an electron transporting layer,an electron injection layer, etc. The organic compound layer may be asingle layer that emits light, or may have a combination of theabove-mentioned layers.

After forming the organic compound layer, a cathode is formed tocomplete the light emitting element. The laminate of the anode, cathode,and organic compound layer corresponds to the light emitting element.The material used to form the cathode is a metal having a small workfunction (typically a metal belonging to Group 1 or 2 in the periodictable) or an alloy containing the metal.

A first insulating layer is formed from an organic resin material tocover an end of the anode. The first insulating layer is provided toprevent short circuit between the anode and the cathode that is formedafter the anode is formed.

The transparent conductive film used as the anode transmits visiblelight and therefore allows light emitted from the organic compound layerto pass therethrough. However, the transparent conductive film has adrawback of high resistivity compared to the resistivity of a metal.High film resistance of the anode formed of the transparent conductivefilm brings difficulty to injection of carriers and lowers the number ofcarriers that are re-combined in the light emitting element. Lessrecombinations in the light emitting element correspond to the lightemission mechanism of the light emitting element ceasing to function. Asa result, the light emitting element cannot emit light at a desiredluminance.

SUMMARY OF THE INVENTION

The present invention has been made in view of the above, and an objectof the present invention is therefore to provide a light emitting devicein which reduction of recombinations in a light emitting element isprevented by employing a low-resistant electrode structure.

According to the present invention, a light emitting device has a lightemitting element composed of first and second electrodes and an organiccompound layer that is sandwiched between the first and secondelectrodes, and the device is characterized in that one of the first andsecond electrodes has a transparent conductive film, a transparentconductive resin formed on the transparent conductive film, and aplurality of conductors formed on the transparent conductive resin. Thepresent invention obtains the effect of lowering the resistance of thetransparent conductive film by forming the plural conductors in thefirst or second electrode. In this specification, an electrode above theorganic compound layer is called a first electrode (upper electrode) andan electrode below the organic compound layer is called a secondelectrode (lower electrode). The term transparent conductive resinrefers to a conductive resin that has 75% or higher light transmittance,preferably, 90% or higher.

According to the present invention, a light emitting device has aplurality of light emitting elements each composed of first and secondelectrodes and an organic compound layer that is sandwiched between thefirst and second electrodes, and the device is characterized in that oneof the first and second electrodes has a transparent conductive film, atransparent conductive resin formed on the transparent conductive film,and a plurality of conductors formed on the transparent conductiveresin, and that a partition wall is formed between adjacent lightemitting elements.

According to the present invention, the light emitting device ischaracterized in that an opening is formed between adjacent conductors,and that light emitted from the organic compound layer reaches outsidethrough the opening.

When a light emitting device has an opening, a voltage cannot uniformlybe applied to its organic compound layer to make it impossible to obtainsufficient light emission. However, this is not a problem in the lightemitting device of the present invention, because the transparentconductive resin is formed to be brought into contact with thetransparent conductive film and with the cover member having the pluralconductors and opening. In other words, in the present invention, theelectric field is uniformly applied to the organic compound layerbecause the present invention can make the transparent conductive resinfunction as a part of the electrodes. The transparent conductive resinalso has a function of bonding the transparent conductive film to theplural conductors and the cover member. In this specification, the termcover member refers to a substrate that faces an element substrate andis bonded to the element substrate with a seal pattern sandwichedbetween the substrates.

The light emitting device of the present invention is characterized inthat a seal pattern is formed outside the light emitting element andthat an opening is formed in the seal pattern. With the opening formedin the seal pattern, the transparent conductive resin can be injectedthrough the opening.

According to the present invention, a light emitting device has a lightemitting element electrically connected to a TFT, and is characterizedin that an insulating film, a transparent conductive film, a transparentconductive resin, and a plurality of conductors are formed above a gateelectrode of the TFT, or above a gate wiring line connected to the TFT,or above a source wiring line connected to the TFT, or above a drainwiring line connected to the TFT, or above a current supplying lineconnected to the TFT, the transparent conductive film being formed onthe insulating film, the transparent conductive resin being formed onthe transparent conductive film, the plural conductors being formed onthe transparent conductive resin. Having the above-mentionedcharacteristic, the present invention can reduce the resistance of thetransparent conductive film without lowering the aperture ratio.

The light emitting device of the present invention is characterized inthat each of the conductors is 0.5 to 5 μm in width. The light emittingdevice of the present invention is characterized in that the opening is10 to 100 μm in width.

A high molecular weight material can be used for the transparentconductive resin. A low molecular weight material refers to a materialthat is lower in molecular weight than a high molecular weight material.

Light obtained from the light emitting element may be one or both oflight emission by singlet excitation and light emission by tripletexcitation.

BRIEF DESCRIPTION OF THE DRAWINGS

In the accompanying drawings:

FIGS. 1A to 1D are diagrams showing a process of manufacturing a lightemitting device of the present invention;

FIGS. 2A to 2C are diagrams showing a process of manufacturing a lightemitting device of the present invention;

FIGS. 3A and 3B are diagrams showing the top structure of a lightemitting device and the circuit structure thereof of the presentinvention;

FIG. 4 is a diagram showing the top structure of a light emitting deviceand the circuit structure thereof of the present invention;

FIGS. 5A to 5F are diagrams showing shapes of electrodes of conductorsof the present invention;

FIG. 6 is a diagram showing the element structure of a light emittingelement of the present invention;

FIG. 7 is a diagram showing the element structure of a light emittingelement of Embodiment 2;

FIGS. 8A and 8B are diagrams of a light emitting device with FIG. 8Ashowing the top structure thereof and FIG. 8B showing the sectionalstructure thereof of Embodiment 4;

FIG. 9 is a diagram showing the sectional structure of a light emittingdevice of Embodiment 4;

FIGS. 10A and 10B are diagrams showing the top structure of a lightemitting device and the circuit structure thereof of Embodiment 5;

FIG. 11 is a diagram showing the sectional structure of a light emittingdevice of Embodiment 7;

FIG. 12 is a diagram showing the sectional structure of a light emittingdevice of Embodiment 8; and

FIGS. 13A to 13H are diagrams showing examples of electric apparatus ofEmbodiment 9.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment Mode

An embodiment mode of the present invention will be described withreference to FIGS. 1A to 4.

In FIG. 1A, thin film transistors are formed on a substrate 101. Thesubstrate 101 in this embodiment mode is a glass substrate, but a quartzsubstrate, a silicon substrate, a metal substrate, or a ceramicsubstrate may be used instead.

Next, a crystalline silicon film is formed into a thickness of 50 nm.The crystalline silicon film can be formed by a known method.

The crystalline silicon film is patterned to form an island-likecrystalline silicon film 102 and an island-like crystalline silicon film103 (102 and 103 are hereinafter referred to as active layers). Asilicon oxide film is formed as a gate insulating film 104 to cover theactive layers 102 and 103. A gate electrode 105 and a gate electrode 106are formed on the gate insulating film 104. The material of the gateelectrodes 105 and 106 is a tungsten film, or a tungsten alloy film,with a thickness of 350 nm. The gate electrodes 105 and 106 are a partof a gate wiring line 301 as shown in FIG. 3A.

Using the gate electrodes 105 and 106 as masks, the active layers 102and 103 are doped with an element that belongs to Group 13 in theperiodic table (typically boron) as shown in FIG. 1B. A known method canbe employed to dope the active layers with the element. Thus formed areimpurity regions 107 to 111 having the p type conductivity (hereinafterreferred to as p type impurity regions). Channel formation regions 112to 114 are defined below the gate electrodes 105 and 106. The p typeimpurity regions 107 to 111 individually serve as source regions ordrain regions of the TFTs.

Next, a protective film (here, a silicon nitride film) 115 is formedinto a thickness of 50 nm. Then the element belonging to Group 13 in theperiodic table, which has been used to dope the active layers, isactivated by heat treatment. The activation can be achieved by furnaceannealing, laser annealing, or lamp annealing, or by a combination ofthese annealing methods. In this embodiment mode, heat treatment isconducted at 500° C. for four hours in a nitrogen atmosphere.

It is effective to conduct hydrogenation treatment after the activationis finished. A known hydrogen annealing technique or plasmahydrogenation technique can be employed for the hydrogenation treatment.

Next, as shown in FIG. 1C, a first interlayer insulating film 116 isformed from an organic resin such as polyimide, acrylic, orpolyimideamide to have a thickness of 800 nm. The organic resin isapplied by a spinner and then heated to be burnt or polymerized, therebyobtaining a flat surface. Organic resin materials in general are low indielectric constant and therefore can reduce parasitic capacitance. Thefirst interlayer insulating film 116 may instead be an inorganicinsulating film.

Next, a second interlayer insulating film 117 is formed on the firstinterlayer insulating film 116 so that gas leakage from the firstinterlayer insulating film 116 does not affect the light emittingelement. The second interlayer insulating film 117 is an inorganicinsulating film, typically, a silicon oxide film, a silicon oxynitridefilm, or a silicon nitride film, or a laminate having theabove-mentioned insulating films in combination. The second interlayerinsulating film is formed by plasma CVD in which the reaction pressureis set to 20 to 200 Pa, the substrate temperature to 300 to 400° C., andthe power density to 0.1 to 1.0 W/cm² at high frequency (13.56 MHz) forelectric discharge. Alternatively, the surfaces of the first and secondinterlayer insulating films 116 and 117 are subjected to plasmatreatment to form a cured film that contains one or more kinds of gaselements selected from the group consisting of hydrogen, nitrogen,carbon halide, hydrogen fluoride, and noble gas.

Thereafter, a resist mask having a desired pattern is formed and contactholes reaching drain regions of the TFTs are formed to form wiring lines118 to 121. The wiring lines are obtained by patterning into a desiredpattern a conductive metal film that is formed from Al or Ti or from analloy of Al or Ti by sputtering or vacuum evaporation. The wiring lines118 and 119 respectively function as a source wiring line and a gatewiring line.

The TFTs are completed through the above-mentioned steps. In the lightemitting device of this embodiment mode, a switching TFT 201 and acurrent controlling TFT 202 are formed as shown in FIG. 1C. Though notshown in FIG. 1C, an erasing TFT 203 of FIGS. 3A and 3B is also formedat the same time. A gate electrode of the erasing TFT 203 is a part of agate wiring line 302. The gate wiring line 302 and a gate wiring line301 that forms a gate electrode of the switching TFT 201 are separatewiring lines. The TFTs in this embodiment mode are all p-channel TFTsbut the present invention is not limited thereto. N-channel TFTs can bealso used. The conductivity type of the TFTs can be set at designer'sdiscretion.

A capacitor storage 305 shown in FIGS. 3A and 3B is also formed at thesame time as the TFTs are formed. The storage capacitor 305 is composedof a storage capacitor and another storage capacitor. The former storagecapacitor is positioned below a wiring line that forms the gateelectrode 106 and includes a semiconductor layer 306, the gateinsulating film 104, and the wiring. The semiconductor layer 306 isformed at the same time the active layers of the TFTs are formed. Thelatter storage capacitor includes the wiring line that forms the gateelectrode 106, the protective film 115, the first interlayer insulatingfilm 116, the second interlayer insulating film 117, and a currentsupplying line 304. The semiconductor layer 306 is electricallyconnected to the current supplying line 304.

Next, a conductive film is formed and then the conductive film is etchedas shown in FIG. 1D to complete the lower electrode 122. The lowerelectrode 122 acts as a cathode or an anode depending on whether itswork function is larger or smaller than the work function of an upperelectrode 124. The conductive film is desirably 0.1 to 1 μm inthickness.

Thereafter, an organic resin film is formed on the entire surface frompolyimide, acrylic, or polyimideamide. A thermally-curable material thatis cured by heating or a photosensitive material that is cured byirradiation of ultraviolet ray is employed for the organic resin film.When a thermally-curable material is used, a resist mask is formed afterthe organic resin film is formed on the entire surface, and aninsulating layer 123 having an opening above the lower electrode 122 isformed by dry etching. When a photosensitive material is employed, aphoto mask is formed after the organic resin film is formed on theentire surface and an insulating layer 123 is formed above the lowerelectrode 122 through exposure and development using the photo mask. Ineither case, the insulating layer 123 is formed to have a tapered edgeand cover an end portion of the lower electrode 122. Having the edgetapered, the insulating layer can be covered well with an organiccompound layer that is to be formed subsequently.

An organic compound layer 130 is formed next. The organic compound layer130 is a laminate having a hole generating layer, a light emittinglayer, a hole injection layer, a hole transporting layer, a holeblocking layer, an electron transporting layer, an electron injectionlayer, a buffer layer, etc. suitably selected in combination. Theselayers may be formed of low molecular weight materials or high molecularweight materials.

Then a transparent conductive film 126 is formed. A transparentconductive high molecular weight material such as ITO is used for thetransparent conductive film 126. Preferably, the thickness of thetransparent conductive film 126 is 80 to 200 nm. If an ITO film isemployed, the film is formed by sputtering. If other transparentconductive high molecular weight materials are chosen, the film isformed by spin coating.

If the organic compound layer 130 is formed on the lower electrode 122so as to obtain a flat surface, defects such as dark spot and lightemission failure of the light emitting element due to short circuitbetween the lower electrode 122 and the transparent conductive film 126can be prevented. (FIG. 2A)

As shown in FIG. 2B, a metal is deposited by evaporation on a covermember 128 and the obtained metal film is patterned to form conductors131 on the cover member 128. The metal that can be used in thisembodiment mode is silver, gold, platinum, palladium, aluminum,magnesium, calcium, indium, copper, neodium, nickel, tin, chromium, orthe like. The cover member 128 is bonded to the substrate in a laterstep as shown in FIG. 3A. Then, a width A of each conductor in a pixelis 0.5 to 5.0 μm (preferably 1.0 to 2.0 μm), and a width B (of anopening 132) that is the distance between two adjacent conductors is 10to 100 μm (preferably 20 to 30 μm). The width B of the opening isappropriately 5 to 15 times the width A. For example, a preferableopening width is 10 to 30 μm when each conductor is 2.0 μm in width.

The cover member 128 may be a glass substrate or a quarts substrate, ora plastic substrate formed of FRP (fiberglass-reinforced plastic), PVF(polyvinyl fluoride), Mylar, polyester, acrylic, or the like. The covermember may be stepped so that a drying agent can be sealed therein.

Subsequently, the device shown in FIG. 2A is bonded to the device shownin FIG. 2B. Specifically, a seal pattern (not shown in the drawing) isformed along the end faces (perimeter) of the cover member 128. Then atransparent conductive resin 129 is applied to the surface of the covermember 128 inside the seal pattern. This embodiment mode employs as thetransparent conductive resin 129 polypyrrole, polyaniline,polythiophene, poly(3,4-ethylene dioxythiophene), polyisothianaphthene,polyacetylene, tetracyanoquinodimethane, a polyvinyl chloridecomposition, or a high molecular weight material mainly containing anaromatic amine polymer. The resin 129 may also be a compound of thesematerials. The above-mentioned materials may be suitably doped withdopants.

Keeping the interior of a vacuum exhaust apparatus at a vacuum state andapplying a constant pressure to the substrate 101 and the cover member128, the substrate 101 is bonded to the cover member 128. The substrate101 and the cover member 128 are bonded such that the side of thesubstrate 101 on which the organic compound layer 130 is formed opposesthe side of the cover member 128 on which the conductors 131 are formed.At this point, the seal member formed on the cover member 128 is heatedand cured.

Thus completed is a light emitting device having a light emittingelement 127 that is composed of the upper electrode 124, the lowerelectrode 122, and the organic compound layer 130. The upper electrode124 is composed of the transparent conductive film 126, the transparentconductive resin 129, and the conductors 131. The conductors 131 and theopening 132 are formed above the light emitting element 127 that iselectrically connected to the TFTs. The transparent conductive film, thetransparent conductive resin on the transparent conductive film, and theconductors on the transparent conductive resin are also formed above thegate electrodes on the TFTs, above the source wiring lines connected tothe TFTs, above the gate wiring lines connected to the TFTs, above thedrain wiring lines connected to the TFTs, and above the currentsupplying line connected to the TFTs.

As described above, a light emitting device having a low-resistantconductive film can be obtained by forming the transparent conductivefilm 126, the conductors 131, and the transparent conductive resin 129sandwiched between the transparent conductive film 126 and theconductors 131 as described above.

Since the opening 132 is formed between adjacent conductors in thepixel, light emitted from the organic compound layer 130 can reachoutside through the opening 132. As a result, the light emitting elementcan emit light upward. The transparent conductive film of the lightemitting element 127 in the present invention is not limited to atransparent material, and therefore a choice of materials that can beused for the electrode is widened.

In the light emitting device of the present invention, the organiccompound layer 130 can be shut off from the outside. To elaborate,external substances that accelerate degradation of the organic compoundlayer 130, such as moisture and oxygen, can be prevented from enteringthe light emitting element. Accordingly, the present inventioneliminates the need for a space filled with inert gas, thereby making itpossible to reduce the thickness of the light emitting device greatly.

FIG. 3A is a top view of the conductors 131.

The conductors 131 are placed above the gate electrodes 105 and 106, thesource wiring line 118, the drain wiring line 120, the gate wiring lines301 and 302, and the current supplying line 304 and in the pixel.

Preferably, the conductors 131 are placed in at least one of thefollowing positions: above the gate electrodes 105 and 106, above thewiring line 118, above the drain wiring line 120, above the gate wiringlines 301 and 302, above the current supplying line 304, and in thepixel, while interposing an insulating film therebetween. Thisarrangement is effective in lowering the resistance of the transparentconductive film 126.

Instead of forming the conductors in the pixel portion, pluralconductors may be formed above a gate electrode having highlight-shielding ability, above a source wiring line, above a gate wiringline, above a drain wiring line, or above a current supplying line whileinterposing an insulating film therebetween. This makes it possible tolower the resistance of the transparent conductive film without reducingthe aperture ratio.

In the present invention, the conductors desirably occupy as small anarea as possible in the pixel. The conductors above the TFTs and thewiring lines desirably occupy as large an area as possible.

As shown in FIG. 4, conductors 431 may be in parallel with a sourcewiring line 418.

FIGS. 3A and 3B and FIG. 4 show conductors forming a stripe pattern inthe pixel. However, the pattern of the conductors are not particularlylimited. For instance, the conductors may be rectangles as shown in FIG.5A, or may be brandied as shown in FIGS. 5B and 5C, or may beelectrically connected to other electrodes as shown in FIGS. 5D and 5E,or may form a grid pattern as shown in FIG. 5F.

In this embodiment mode, the seal pattern is formed on the cover memberand the transparent conductive resin is applied to the cover member tocomplete the light emitting device. However, the present invention isnot limited thereto. The seal pattern may be formed on the substrate andthe transparent conductive resin may be applied to the substrate toobtain the light emitting device.

In this embodiment mode, the transparent conductive resin 129 is appliedto the surface of the cover member inside the seal pattern in a mannersimilar to the liquid crystal drop injection method employed in a liquidcrystal display device manufacturing process. The applied transparentconductive resin 129 is sandwiched between the substrate and the covermember 128 in the light emitting device manufactured in accordance withthe present invention. Alternatively, the seal pattern may have anopening so that the transparent conductive resin is injected through theopening similar to the manner in which a liquid crystal is injectedthrough an injection port in vacuum. If the transparent conductive resinhas high viscosity, the resin may be heated or pressurized. After theinjection, the opening may be closed by an end-sealing material.

The present invention is not limited to the TFT structures employed inthis embodiment mode but may take the inverted stagger structure or thetop gate structure.

Embodiment 1

This embodiment describes the structure of a light emitting element of alight emitting device according to the present invention. Thedescription is given with reference to FIG. 6.

In FIG. 6, reference symbol 501 denotes a lower electrode, which is afilm of a metal such as platinum (Pt), chromium (Cr), tungsten (W), ornickel (Ni). The lower electrode 501 corresponds to an anode. The roleof the lower electrode 501 in this embodiment is to inject holes to anorganic compound layer when a voltage is applied. Therefore, thematerial of the lower electrode 501 is required to be higher in HOMOlevel than the organic compound that forms the organic compound layer.In other words, the lower electrode is desirably formed from a materialhaving a large work function.

Next, a hole generating layer 504 is formed by co-evaporation of anelectron acceptor 502 and a low molecular weight material 503. In thisembodiment, the material of the electron acceptor 502 can be the samematerial given in Embodiment Mode. The low molecular weight material 503used in this embodiment is a material capable of injecting holes.

The hole generating layer 504 in this embodiment is formed into athickness of 100 to 200 nm by co-evaporation of the low molecular weightmaterial 503 that is a material capable of injecting holes and theelectron acceptor 502.

The hole generating layer 504 in the present invention is a filmtransmissive of light. Examples of the low molecular weight material 503include condensed rings hydrocarbon such as anthracene, tetracene, orpyrene, normal paraffin, oligothiophene-based materials, andphthalocyanine-based materials. Examples of the electron acceptor 502include TCNQ (tetracyano-quinodimethan), FeCl₃, ZrCl₄, HfCl₄, NbCl₅,TaCl₅, MoCl₅, and WCl₆.

Also, in the case where the hole-generating layer is formed using apolymeric material, the hole-generating layer can be formed by existingthe polymeric material such as polyacetylenes, polythiophenes,poly(3-methyl)thiophenes, poly(3-ethyl) thiophenes, poly(3-n-butyl)thiophenes, poly(3-hexyl) thiophenes, poly (3-octyl) thiophenes, poly(3-dodecyl) thiophenes, poly (3-octadecyl)thiophenes,poly(3-eicosyl)thiophenes and poly(3-methyl-Co-butyl) thiophenestogether with the electron acceptor 502 (acceptor) such as PF6-, bromineand iodine in a solvent and using the printing method, the ink jetmethod or the spin coating method.

When forming the hole generating layer 504, the molar ratio of the lowmolecular weight material 503 to the electron acceptor 502 is desirably1:1. Electric charges move between an organic material and the electronacceptor 502 when an electron of the organic material is pulled out ofthe organic material by the electron acceptor 502, thereby generatingholes from the organic material. Accordingly, holes are injected fromthe lower electrode upon application of a voltage and the density ofholes flowing is raised. The presence of the hole generating layer 504makes it possible to form the organic compound layer uniformly and toapply electric field uniformly to the organic compound layer, as well.Therefore a highly reliable light emitting element can be formed.

Next, a hole injection layer 505, a hole transporting layer 506, a lightemitting layer 507, and an electron transporting layer 508 are layered.

The hole injection layer 505 is formed from a material capable ofinjecting holes. This embodiment employs the same low molecular weightmaterial that the hole generating layer 504 uses to form the holeinjection layer 505 to have a thickness of 10 to 30 nm. By forming thehole generating layer 504 and the hole injection layer 505 from the samelow molecular weight material, the energy barrier between the two layersis lowered to make it easy for carriers to move.

The hole transporting layer 506 is formed from a material capable oftransporting holes. This embodiment uses as a material capable oftransporting holes an aromatic amine-based material such as4,4′-bis[N-(1-naphthyl)-N-phenyl-amino]biphenyl (denoted by α-NPD),1,1-bis[4-bis(4-methylphenyl)-amino-phenyl]cyclohexane (denoted byTPAC), or 4,4′,4″-tris[N-(3-methylphenyl)-N-phenyl-amino]triphenyl amine(denoted by MTDATA). The thickness of the hole transporting layer 506 is30 to 60 nm.

The light emitting layer 507 is formed from a luminous material. Thisembodiment uses as a luminous material Alq3 or Alpq3 that is obtained byintroducing phenyl base to Alq3. The thickness of the light emittinglayer 507 is 30 to 60 nm. The light emitting layer 507 may be doped witha dopant. The dopant can be a known material such as perylene, rubrene,coumarin, 4-(dicyanomethylene)-2-methyl-6-(p-dimethylaminostylil)-4H-pyran (denoted by DCM), or quinacridon.

The light emitting layer 507 may be formed by co-evaporation of CBP andan iridium complex (Ir(ppy)₃) or a platinum complex. CBP is a dopant andthe iridium complex emits light by triplet excitation. In this case, ahole blocking layer has to be formed between the light emitting layer507 and the electron transporting layer 508. The hole blocking layer isformed from BCP to have a thickness of 10 to 30 nm.

The electron transporting layer 508 is formed from a material capable oftransporting electrons. This embodiment employs as a material capable oftransporting electrons a 1,3,4-oxadiazole derivative, a 1,2,4-triazolederivative, or the like. Specifically, the material that can be used forthe layer 508 is2-(4-biphenylyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole (denoted byPBD), 2,5-(1,1′-dinaphthyl)-1,3,4-oxadiazole (denoted by BND), 1,3-bis[5-(p-tert-butylphenyl)-1,3,4-oxadiazole-2-Ile]benzene (denoted byOXD-7), or3-(4-tert-butylphenyl)-4-phenyl-5-(4-biphenylyl)-1,2,4-triazole (denotedby TAZ). The thickness of the electron transporting layer 508 is 30 to60 nm.

The hole generating layer 504, the hole injection layer 505, the holetransporting layer 506, the light emitting layer 507, and the electrontransporting layer 508 (and the blocking layer) together make an organiccompound layer 509. After the organic compound layer 509 is formed, atransparent conductive film 510 is formed. In this embodiment, ITO isused to form the transparent conductive film 510 of the light emittingelement.

Conductors 511 are formed on a cover member (not shown in the drawing)and an opening 512 is formed in the cover member. This is achieved inthis embodiment by evaporation of silver through sputtering andsubsequent patterning. The patterning employs etching and a mixture ofhydrogen fluoride and nitric acid as etchant. The conductors 511 formedon the cover member (not shown) are bonded to the transparent conductivefilm 510 in vacuum with a transparent conductive resin 513 sandwichedtherebetween. The transparent conductive resin 513 may be applied to thecover member (not shown) or injected from an opening (not shown in thedrawing) of the seal pattern as in the above-mentioned Embodiment Mode.The transparent conductive resin 513 of this embodiment is a highmolecular weight material mainly containing a polyvinyl chloridecomposition or an aromatic amine polymer. A polyvinyl chloridecomposition is a material composed of a vinyl chloride resin, aplasticizer (for example, phthalate esters or glycol esters), andlithium salt (lithium chloride, (trifluoromethane sulfonyl) imidelithium, or the like). An aromatic amine polymer is a polymer such asaminonaphthalenes and aminoquinoline.

The transparent conductive resin 513 is formed on the transparentconductive film 510. The conductors 511 and the opening 512 are formedon the transparent conductive resin 513. In this specification, theconductors 511, the transparent conductive resin 513, and thetransparent conductive film 510 are together called an upper electrode514. The light is emitted in the direction indicated by the arrow inFIG. 6.

As described above, the upper electrode 514 is made up of thetransparent conductive film 510, the transparent conductive resin 513,and the conductors 511 to obtain a light emitting device that has alow-resistant conductive film.

Transparent and conductive materials are employed for the transparentconductive film 510 and the transparent conductive resin 513, and theopening 512 is provided between adjacent conductors. Therefore lightemitted from the organic compound layer 509 can reach outside throughthe opening 512. This allows the organic compound layer to emit lightupward. A light-shielding material may be employed for the lowerelectrode 501.

The present invention employs a sealing method in which the contactbetween the organic compound layer 509 and oxygen or moisture is avoidedby forming the transparent conductive resin 513 between the transparentconductive film 510 and the conductors 511. Accordingly, there is noneed to provide a space filled with inert gas, making it possible toreduce the thickness of the light emitting device greatly.

The lower electrode 501 serves as an anode and the upper electrode 514serves as a cathode in this embodiment, but the present invention is notlimited thereto. The lower electrode 501 can be a cathode whereas theupper electrode 514 serves as an anode. In this case, the electrontransporting layer, light emitting layer, hole transporting layer, holeinjection layer, and hole generating layer of the organic compound layerare layered in this order with the electron transporting layer being theclosest to the lower electrode.

Embodiment 2

This embodiment describes a case of forming a mixture layer in the lightemitting element of Embodiment 1. The description will be given withreference to FIG. 7.

In FIG. 7, reference symbol 601 denotes a lower electrode and 602denotes a hole generating layer that is formed by co-evaporation of anelectron acceptor and a low molecular weight material.

A hole injection layer 603, a hole transporting layer 604, a lightemitting layer 605, and an electron transporting layer 606 are laminatedon the hole generating layer 602 to form an organic compound layer 607.Details about the methods of forming these layers may refer toEmbodiment 1.

In this embodiment, the interface between the hole transporting layer604 and the light emitting layer 605 and the interface between theelectron transporting layer 606 and the light emitting layer 605 eachhave a mixture layer.

In this embodiment, the mixture layer formed at the interface betweenthe light emitting layer 605 and the hole transporting layer 604 iscalled a mixture layer (1) 608, whereas the mixture layer formed at theinterface between the light emitting layer 605 and the electrontransporting layer 606 is called a mixture layer (2) 609.

The mixture layer (1) 608 is formed by co-evaporation of the materialfor forming the light emitting layer 605 and the material for formingthe hole transporting layer 604. The ratio of the materials that aremixed to form the mixture layer (1) 608 can be varied.

The mixture layer (2) 609 is formed by co-evaporation of the materialfor forming the light emitting layer 605 and the material for formingthe electron transporting layer 606. The ratio of the materials that aremixed to form the mixture layer (2) 609 can be varied.

After the electron transporting layer 606 is formed, a transparentconductive film 610 is formed by evaporation. In this embodiment, ITO isused to form the transparent conductive film 610 of the light emittingelement.

Conductors 611 are formed on a cover member (not shown in the drawing)and an opening 612 is formed in the cover member. This is achieved inthis embodiment by evaporation of silver through sputtering andsubsequent patterning. The patterning employs etching and a mixture ofhydrogen fluoride and nitric acid as etchant. The conductors 611 formedon the cover member (not shown) are bonded to the transparent conductivefilm 610 in vacuum with a transparent conductive resin 613 sandwichedtherebetween. The transparent conductive resin 613 of this embodiment isa high molecular weight material mainly containing a polyvinyl chloridecomposition or an aromatic amine polymer. A polyvinyl chloridecomposition is a material composed of a vinyl chloride resin, a plasticmaterial (for example, phthalate esters or glycol esters), and lithiumsalt (lithium chloride, (trifluoromethane sulfonyl) imide lithium, orthe like). An aromatic amine polymer is a polymer such asaminonaphthalenes and aminoquinoline.

The transparent conductive resin 613 is formed on the transparentconductive film 610. The conductors 611 and the opening 612 are formedon the transparent conductive resin 613. In this specification, theconductors 611, the transparent conductive resin 613, and thetransparent conductive film 610 are together called an upper electrode614.

As has been described, the mixture layers are formed at the interfacesbetween the light emitting layer 605 and the layers adjacent thereto(specifically, the interface between the light emitting layer 605 andthe hole transporting layer 604 and the interface between the lightemitting layer 605 and the electron transporting layer 606). Thisstructure improves injection of holes from the hole transporting layer604 to the light emitting layer 605 and injection of electrons from theelectron transporting layer 606 to the light emitting layer 605.Accordingly, recombination of carriers in the light emitting layer 605is enhanced. The light is emitted in the direction indicated by thearrow in FIG. 7.

As described above, the upper electrode 614 is made up of thetransparent conductive film 610, the transparent conductive resin 613,and the conductors 611 to obtain a light emitting device that has alow-resistant conductive film.

Transparent and conductive materials are employed for the conductors 611and the transparent conductive resin 613, and the opening 612 isprovided between adjacent conductors. Therefore, light emitted from theorganic compound layer 607 can reach outside through the opening 612.This allows the organic compound layer to emit light upward. Alight-shielding material may be employed for the lower electrode 601.

The present invention employs a sealing method in which the contactbetween the organic compound layer 607 and oxygen or moisture is avoidedby forming the transparent conductive resin 613 between the transparentconductive film 610 and the conductors 611. Accordingly, there is noneed to provide a space filled with inert gas, making it possible toreduce the thickness of the light emitting device greatly.

The lower electrode 601 serves as an anode and the upper electrode 614serves as a cathode in this embodiment, but the present invention is notlimited thereto. The lower electrode 601 can be a cathode whereas theupper electrode 614 serves as an anode. In this case, the electrontransporting layer, mixture layer (2), light emitting layer, mixturelayer (1), hole transporting layer, hole injection layer, and holegenerating layer of the organic compound layer are laminated in thisorder with the electron transporting layer being the closest to thelower electrode.

Embodiment 3

This embodiment gives a description on a light emitting device havinglight emitting elements that respectively emit red light, green light,and blue light. In this embodiment, a lower electrode 122 is formed asshown in FIG. 2A and then organic compound layers that emit light indifferent colors are formed by using different materials for their lightemitting layers. All of the light emitting layers are formed byevaporation, which allows the use of metal mask in forming lightemitting layers of pixels of different colors from different materials.

In this embodiment, a light emitting layer that emits light in red color(hereinafter referred to as red light emitting layer) is formed firstusing a metal mask. A known material can be used as the material of thered light emitting layer of this embodiment. All of the red lightemitting layers to be formed in the light emitting device may be formedsimultaneously. Alternatively, the red light emitting layers may beformed sequentially while moving the metal mask along.

Next, a light emitting layer that emits light in green color(hereinafter referred to as green light emitting layer) is formed usinga metal mask. A known material can be used as the material of the greenlight emitting layer of this embodiment. All of the green light emittinglayers to be formed in the light emitting device may be formedsimultaneously. Alternatively, the green light emitting layers may beformed sequentially while moving the metal mask along.

Further, a light emitting layer that emits light in blue color(hereinafter referred to as blue light emitting layer) is formed using ametal mask. A known material can be used as the material of the bluelight emitting layer of this embodiment. All of the blue light emittinglayers to be formed in the light emitting device may be formedsimultaneously. Alternatively, the blue light emitting layers may beformed a few at a time while moving the metal mask along.

The above-mentioned steps provide the light emitting device having lightemitting elements that respectively emit red light, green light, andblue light. The colors of light emitted from the light emitting elementsare not limited to those shown in this embodiment. Known materials suchas one that emits white light and one that emits orange light may beused in combination.

Embodiment 4

This embodiment describes the exterior of a light emitting device of thepresent invention with reference to FIGS. 8A and 8B.

FIG. 8A is a top view of the light emitting device and FIG. 8B is asectional view taken along the line A-A′ of FIG. 8A. Reference symbol701 denotes a source signal line driving circuit; 702, a pixel portion;and 703, a gate signal line driving circuit. Denoted by 710 is asubstrate; 704, a cover member; 705, a seal pattern, 707; a transparentconductive resin; 720, conductors; 721, a concave portion; 722, a dryingagent; and 723, a film. The space surrounded by the cover member 704(including the film 723) and the seal pattern 705 is filled with thetransparent conductive resin 707. The light is emitted in the directionindicated by the arrow in FIG. 8B.

Reference symbol 708 represents a connection wiring line fortransmitting signals that are to be inputted to the source signal linedriving circuit 701 and the gate signal line driving circuit 703. Theconnection wiring line 708 receives video signals and clock signals froman FPC (flexible printed circuit) 709 that selves as an external inputterminal. The FPC alone is shown in the drawings but a printed wiringboard (PWB) may be attached to the FPC. In this specification, a lightemitting device refers to a light emitting device itself plus an FPC, orplus an FPC and a PWB.

Next, the sectional structure taken along the line A-A′ in FIG. 8A isdescribed with reference to FIG. 8B. The driving circuits and the pixelportion are formed On the substrate 710. In FIG. 8B, one of the drivingcircuits, namely, the source signal line driving circuit 701, and thepixel portion 702 are shown.

The source signal line driving circuit 701 here is a CMOS circuit havinga p-channel TFT 713 and an n-channel TFT 714 in combination. The drivingcircuit can be any known CMOS circuit, PMOS circuit, or NMOS circuit.This embodiment employs a driver-integrated substrate in which drivingcircuits are formed on a substrate, but the present invention is notlimited thereto. The driving circuits may be external to the substrate.

The pixel portion 702 is composed of a plurality of pixels each of whichincludes a current controlling TFT 711 and a lower electrode 712. Thelower electrode 712 is electrically connected to a drain of the currentcontrolling TFT 711.

An insulator 715 is formed on each end of the lower electrode 712. Anorganic compound layer 717 is formed on the lower electrode 712. Atransparent conductive film 718 is formed on the insulator 715 and theorganic compound layer 717.

The transparent conductive film 718 also functions as a common wiringline shared by all the pixels and is electrically connected to the FPC709 through the connection wiring line 708.

The conductors 720 are formed on the cover member 704. An opening 724 isprovided between the conductors 720. The cover member 704 is bonded tothe substrate 710 in vacuum with the seal pattern 705 interposedtherebetween. The transparent conductive resin 707 is formed between thesubstrate 710 and the cover member 704. Spacers formed from a resin filmmay be provided to keep the distance between the cover member 704 andthe substrate 710. The seal member is preferably an epoxy resin.Desirably, the material of the seal member is one that allows as smallamount of moisture and oxygen as possible to transmit.

In this embodiment, a glass substrate or a quartz substrate is used asthe cover member 704. Alternatively, the cover member may be a plasticsubstrate that is formed of FRP (fiberglass-reinforced plastics), PVF(polyvinyl fluoride), Mylar, polyester, acrylic, or the like.

After the cover member 704 is bonded to the substrate 710 using the sealpattern 705, the side faces (exposed faces) of the device may be furthercovered and sealed by the seal pattern (seal member).

The transparent conductive film 718, the transparent conductive resin707, and the conductors 720 are together called an upper electrode 725.Completed through the above-mentioned steps is a light emitting element719 that is composed of the upper electrode 725, the organic compoundlayer 717, and the lower electrode 712.

The light emitting device of the present invention can lower theresistance of the transparent conductive film 718 by forming theconductors 720 that are electrically connected to the transparentconductive film 718.

Since the opening is formed between the conductors 720, light emittedfrom the organic compound layer 717 can reach outside through theopening 724. As a result, the light emitting element can emit lightupward. The material of the lower electrode 712 of the light emittingelement is not limited to a transparent material, and therefore a choiceof materials that can be used for the lower electrode 7112 is widened.

The present invention employs a sealing method in which the contactbetween the organic compound layer 717 and oxygen or moisture is avoidedby forming the transparent conductive resin 707 between the transparentconductive film 718 and the conductors 720. Accordingly, there is noneed to provide a space filled with inert gas, making it possible toreduce the thickness of the light emitting device greatly.

The structure of this embodiment can be employed when any of the lightemitting elements that are structured in accordance with Embodiments 1through 3 is sealed to obtain a light emitting device.

This embodiment uses glass substrates for the substrate 710 and thecover member 704. However, as shown in FIG. 9, flexible films formedfrom an organic resin may be used for a substrate 1110 and a covermember 1104. If flexible films are employed, the substrate 1110 and thecover member 1104 can be curved. A TFT may be formed on a glasssubstrate to be transferred to a flexible film. In the embodiment of thepresent invention which is illustrated in FIGS. 8A and 8B, the dryingagent 722 is placed above the source signal line driving circuit 701 inorder to allow the organic compound layer to emit light upward. In theembodiment of the present invention which is illustrated in FIG. 9, adrying agent 1122 may be placed outside a seal pattern 1105 a.Alternatively, a sealing pattern 1105 b may be placed outside the dryingagent 1122. Of the substrate and cover member, one may be a glasssubstrate while the other is formed from a flexible film.

Embodiment 5

A description is given with reference to FIG. 10A on the top view of apixel of a light emitting device according to the present invention. Thecircuit structure in FIG. 10A is shown in FIG. 10B.

In FIG. 10A, reference symbol 801 denotes a switching TFT, which is ap-channel TFT. A wiring line denoted by 802 is a gate wiring line thatis electrically connected to gate electrodes 804 (804 a and 804 b) ofthe switching TFT 801.

In this embodiment, the switching TFT has a double gate structure inwhich two channel formation regions are formed. However, a single gatestructure in which one channel formation region is formed or a triplegate structure in which three channel formation regions are formed maybe employed instead.

A source of the switching TFT 801 is connected to a source wiring line805. A drain of the switching TFT 801 is connected to a drain wiringline 806. The drain wiring line 806 is electrically connected to a gateelectrode 808 of a current controlling TFT 807. The current controllingTFT 807 is an n-channel TFT.

In this embodiment, the switching TFT 801 is a p-channel TFT and thecurrent controlling TFT 807 is an n-channel TFT. Alternatively, ann-channel TFT may be used for the switching TFT 801 while a p-channelTFT is used for the current controlling TFT 807, or TFTs 801 and 807 maybe both n-channel TFTs, or TFTs 801 and 807 may be both p-channel TFTs.

A source of the current controlling TFT 807 is electrically connected toa current supplying line 809. A drain of the current controlling TFT 807is electrically connected to a drain wiring line 810. The drain wiringline 810 is also electrically connected to a lower electrode (not shownin the drawing). An organic compound layer is formed on a transparentconductive film (not shown in the drawing) and conductors 831 are formedthereon to complete a light emitting, element 815 shown in FIG. 8B.

A storage capacitor (capacitor) is formed in a region denoted by 812.The storage capacitor 812 is formed among the current supplying line809, a semiconductor layer 813, an insulating film (not shown in thedrawing) on the same layer as a gate insulating film, and a capacitanceelectrode 814. The capacitance electrode 814 is electrically connectedto the gate electrode 808. A capacitor composed of the capacitanceelectrode 814, the same layer (not shown) as an interlayer insulatingfilm, and the current supplying line 809 can also be used as a storagecapacitor.

The conductors are formed above the gate wiring line 802, above the gateelectrodes 804 (804 a and 804 b), above the gate electrode 808, abovethe source wiring line 805, above the drain wiring line 810, above thecurrent supplying line 809, and in the pixel.

The conductors are placed in one of the following positions: above thegate wiring line 802, above the gate electrodes 804 (804 a and 804 b),above the gate electrode 808, above the source wiring line 805, abovethe drain wiring line 810, above the current supplying line 809, and inthe pixel, while interposing an insulating film therebetween. Thisarrangement is effective in lowering the resistance of the transparentconductive film.

The pixel portion structure described in this embodiment can replace thepixel portion structure of Embodiment Mode.

Embodiment 6

This embodiment describes a case of forming a high molecular weight holegenerating layer from a high molecular weight material and an electronacceptor. This embodiment is identical with the above-mentionedEmbodiment Mode except the materials of the hole generating layer andthe method of forming the hole generating layer.

As the polymeric material for forming the hole-generating layer,polyacetylenes, polythiophenes, poly(3-methyl)thiophenes,poly(3-ethyl)thiophenes, poly(3-n-butyl)thiophenes, poly(3-hexyl)thiophenes, poly(3-octyl)thiophenes, poly(3-dodecyl)thiophenes,poly(3-octadecyl)thiophenes, poly(3-eicosyl)thiophenes,poly(3-methyl-Co-butyl)thiophenes, or the like, which is a conjugatedpolymeric material, can be used. The hole-generating layer is formed bydissolving or dispersing in the solvent the above-mentioned polymericmaterial together with the dopant such as PF6-, bromine and iodine.

Furthermore, poly(3-hexyl)thiophenes, poly(3-octyl)thiophenes,poly(3-dodecyl)thiophenes, poly(3-octadecyl)thiophenes,poly(3-eicosyl)thiophenes and poly(3-methyl-Co-butyl)thiophenes aresoluble. As the solvent, chloroform, benzene, tetralin, or the like canbe used.

In this embodiment, a hole generating layer 504 with a thickness of 10to 50 nm (preferably 20 to 30 nm) is formed on a lower electrode 501shown in FIG. 6. The hole generating layer 504 is formed from a solublematerial by printing or by the ink jet method.

Alternatively, the hole generating layer 504 may be formed by spincoating. In this case, the hole generating layer 504 is shared byadjacent electrodes, and therefore the distance between the adjacentelectrodes has to be large to increase the resistance thereof. Theresistance of the adjacent electrodes (anodes) has to be set to{fraction (1/10)} or more of the resistance between electrodes(cathodes) that face the anodes.

An organic compound layer 509 is formed on the hole generating layer504. The organic compound layer 509 is a combination of a hole injectionlayer 505, a hole transporting layer 506, a light emitting layer 507,and an electron transporting layer 508. In this embodiment, knownmaterials are used to form the hole injection layer, the holetransporting layer, the light emitting layer, and the electrontransporting layer.

After the organic compound layer 509 is formed in this way, an ITO filmis formed as a transparent conductive film 510 on the organic compoundlayer 509.

Conductors 511 are formed on a cover member (not shown in the drawing)and an opening 512 is formed in the cover member. The conductors 511formed on the cover member (not shown) are bonded to the transparentconductive film 510 in vacuum with a transparent conductive resin 513sandwiched therebetween.

In the light emitting device of the present invention, the organiccompound layer 509 having a laminate structure is formed between thetransparent conductive film 510 and the conductors 511, and the samematerial is used to form the hole generating layer 504 and the holeinjection layer 505.

The transparent conductive resin 513 is formed on the transparentconductive film 510. The conductors 511 and the opening 512 are formedon the transparent conductive resin 513. In this specification, theconductors 511, the transparent conductive resin 513, and thetransparent conductive film 510 are together called an upper electrode514. The light is emitted in the direction indicated by the arrow inFIG. 6.

Thus completed is a light emitting element composed of the lowerelectrode 501, the organic compound layer 509, and the upper electrode514.

The light emitting device of the present invention can lower theresistance of the transparent conductive film 510 by forming theconductors 511 that are electrically connected to the transparentconductive film 510.

Transparent and conductive materials are employed for the transparentconductive film 510 and the transparent conductive resin 513, and theopening 512 is provided between adjacent conductors. Therefore, lightemitted from the organic compound layer 509 can reach outside throughthe opening 512. This allows the organic compound layer to emit lightupward. A light-shielding material may be employed for the lowerelectrode 501.

The present invention employs a sealing method in which the contactbetween the organic compound layer 509 and oxygen or moisture is avoidedby forming the transparent conductive resin 513 between the transparentconductive film 510 and the conductors 511. Accordingly, there is noneed to provide a space filled with inert gas, making it possible toreduce the thickness of the light emitting device greatly.

The lower electrode 501 serves as an anode and the upper electrode 514serves as a cathode in this embodiment, but the present invention is notlimited thereto. The lower electrode 501 can be a cathode whereas theupper electrode 514 serves as an anode. In this case, the electrontransporting layer, tight emitting layer, hole transporting layer, holeinjection layer, and hole generating layer of the organic compound layerare layered in this order with the electron transporting layer being theclosest to the lower electrode.

The structure of this embodiment may be combined with any of thestructures of Embodiments 1 through 6.

Embodiment 7

A description is given with reference to FIG. 11 on an example ofapplying the present invention to TFTs that are structured differentlyfrom the TFTs of Embodiment 4.

Reference symbol 1001 denotes a substrate; 1002, a gate electrode; 1003,a source wiring line; 1004, a capacitance wiring line; and 1005, a firstinsulating film. 1006 denotes a source wiring line; 1007 and 1008,channel formation regions; 1009, a source or drain region; and 1010, anLDD region. 1011 denotes a drain region; 1012, an LDD region; 1013 and1014, third insulating films; and 1015, a fourth insulating film. 1016denotes a first interlayer insulating film, 1017, a connection wiringline; 1018, a source or drain wiring line; 1019, a drain wiring line;and 1020, a lower electrode. 1021 denotes a second interlayer insulatingfilm; 1022, an organic compound layer; 1023, a transparent conductivefilm; 1024, a transparent conductive resin; and 1025, a cover member.1026 denotes conductors; 1027, a light emitting element; and 1028, anopening. The arrow in FIG. 11 indicates the direction of light emittedfrom the organic compound layer 1022.

In this specification, the conductors 1026, the transparent conductiveresin 1024, and the transparent conductive film 1023 are together calledan upper electrode 1029. The lower electrode 1020, the organic compoundlayer 1022, and the upper electrode 1029 constitute the light emittingelement 1027.

The light emitting device of this embodiment can lower the resistance ofthe transparent conductive film 1023 by forming the conductors 1026 thatare electrically connected to the transparent conductive film 1023.

Since the opening 1028 is provided between adjacent conductors, lightemitted from the organic compound layer 1022 can reach outside throughthe opening 1028. This allows the organic compound layer to emit lightupward. The conductors 1026 of the light emitting element 1027 thereforedo not need to be transparent, which widens a choice of materials of theelectrodes.

The present invention employs a sealing method in which the contactbetween the organic compound layer 1022 and oxygen or moisture isavoided by forming the transparent conductive resin 1024 between thetransparent conductive film 1023 and the conductors 1026 Accordingly,there is no need to provide a space filled with inert gas, making itpossible to reduce the thickness of the light emitting device greatly.

Embodiment 8

The present invention can be applied to a passive-type light emittingdevice. A description is made of an example of applying the presentinvention to the passive-type light emitting device with reference toFIG. 12.

Reference symbol 900 denotes a substrate; 901, a light emitting element;902, an upper electrode; 903, a first insulating film; 904, a secondinsulating film; 905, a seal pattern; 906 a transparent conductiveresin; 907, a lower electrode; 908, an organic compound layer; 909, atransparent conductive film; 910, a third insulating film; 911, a fourthinsulating film; 912, a cover material; 913, conductors; 914, openingportion; and 915, partition wall. The arrow indicates the direction oflight emitted from the organic compound layer 908.

The partition walls 915 are patterned into a desired shape byphotolithography at given positions. The material of the partition wallsis NN700 (a product of JSR Corporation) having a photosensitive acrylicmaterial as its main ingredient. NN700 is applied by a spinner to theentire surface of the cover member 912 on which the conductors 913 areformed. The thickness of the NN700 film is set to 1.4 μm. After applyingand calcinating NN700, the NN700 film is exposed using a photo mask anda mask aligner. Thereafter the film is developed with a developer mainlycontaining TMAH (tetramethyl ammonium hydroxide). The substrate is letdry and then subjected to baking at 250° C. for an hour. As a result,partition walls for insulating adjacent light emitting elements fromeach other are obtained as shown in FIG. 12. The height of eachpartition wall is 1.2 μm after the baking.

The transparent conductive resin 906 may be formed by application orinjection, or by the ink jet method.

In this specification, the conductors 913, the transparent conductiveresin 906, and the transparent conductive film 909 are together calledan upper electrode 902. The light is emitted in the direction indicatedby the arrow in FIG. 12. Thus completed is a light emitting element 901composed of the lower electrode 907, the organic compound layer 908, andthe upper electrode 902.

Further, the light emitting device of this embodiment can lower theresistance of the transparent conductive film 909 by forming theconductors 913 that are electrically connected to the transparentconductive film 909.

Since the opening 914 is provided between adjacent conductors, lightemitted from the organic compound layer 908 can reach outside throughthe opening 914. This allows the organic compound layer to emit lightupward. The conductors 913 of the light emitting element 901 thereforedo not need to be transparent, which widens a choice of materials of theelectrodes.

The present invention employs a sealing method in which the contactbetween the organic compound layer 908 and oxygen or moisture is avoidedby forming the transparent conductive resin 906 between the transparentconductive film 909 and the conductors 913. Accordingly, there is noneed to provide a space filled with inert gas, making it possible toreduce the thickness of the light emitting device greatly.

Embodiment 9

Light emitting devices with light emitting elements are self-luminousand therefore have superior visibility in bright surroundings as well aswider viewing angle compared to liquid crystal display devices.Accordingly, light emitting devices with light emitting elements can beused in display units of various electric apparatuses.

An electric apparatus using a light emitting device that is manufacturedin accordance with the present invention can be a video camera, adigital camera, a goggle type display (head mounted display), anavigation system, an audio replaying device (such as a car audio systemand an audio component), a notebook computer, a game machine, a portableinformation terminal (such as a mobile computer, a cellular phone, aportable game machine, and an electronic book), an image reproducingdevice provided with a recording medium (specifically, a device having adisplay device capable of displaying an image that is retrieved from arecording medium such as a DVD (digital versatile disc)), etc. Lightemitting devices with light emitting elements are particularly preferredin portable information terminals of which screens are often slantedwhen viewed and therefore required to have wide viewing angle. Specificexamples of these electric appliances are shown in FIGS. 13A to 13H.

FIG. 13A shows a display device, which is composed of a case 2001, asupporting base 2002, a display unit 2003, speaker units 2004, a videoinput terminal 2005, etc. The light emitting device manufactured inaccordance with the present invention can be used as the display unit2003. Light emitting devices with light emitting elements areself-luminous and do not need back light, thereby making it possible toobtain thinner display units than those utilizing liquid crystal displaydevices. The term display device includes all display devices fordisplaying information, such as personal computer monitors, displaydevices for receiving TV broadcasting, and display devices foradvertising.

FIG. 13B shows a digital still camera, which is composed of a main body2101, a display portion 2102, an image receiving portion 2103, anoperation key 2104, an outer connection port 2105, a shutter 2106 etc.The light emitting device manufactured in accordance with the presentinvention can be used as the display unit 2102.

FIG. 13C shows a notebook computer, which is composed of a main body2201, a case 2202, a display portion 2203, a keyboard 2204, an outerconnection port 2205, a pointing mouse 2206 etc. The light emittingdevice manufactured in accordance with the present invention can be usedas the display unit 2203.

FIG. 13D shows a mobile computer, which is composed of a main body 2301,a display portion 2302, a switch 2303, an operation key 2304, aninfrared port 2305 etc. The light emitting device manufactured inaccordance with the present invention can be used as the display unit2302.

FIG. 13E shows a portable image reproducing device provided with arecording medium (specifically, a DVD player). The device is composed ofa main body 2401, a case 2402, a display unit A 2403, a display unit B2404, a recording medium (DVD etc.) reading unit 2405, operation keys2406, speaker units 2407, etc. The display unit A 2403 mainly displaysimage information whereas the display unit B 2404 mainly displays textinformation. The light emitting device manufactured in accordance withthe present invention can be used for the display unit A 2403 and thedisplay unit B 2404 both. An image reproducing device provided with arecording medium includes a household game machine.

FIG. 13F shows a goggle-type display (head mount display), which iscomposed of a main body 2501, a display portion 2502, and an arm portion2503. The light emitting device manufactured in accordance with thepresent invention can be used as the display unit 2502.

FIG. 13G shows a video camera, which is composed of a main body 2601, adisplay portion 2602, a case 2603, an outer connection port 2604, aremote control receiving portion 2605, an image receiving portion 2606,a battery 2607, an audio input portion 2608, an operation key 2609, aneye piece portion 2610, etc. The light emitting device manufactured inaccordance with the present invention can be used as the display unit2602.

FIG. 13H shows a portable image taking display apparatus, which iscomposed of a main body 2701, a display portion 2702, an image receivingportion 2703, an operation switch 2704, a battery 2705, etc. The lightemitting device manufactured in accordance with the present invention,especially shown FIG. 9 can be used as the display unit 2702. Beingcurved itself, the light emitting device of the present invention can beeffectively built in a three-dimensionally curved electric apparatusthat is designed on the basis of ergonomics.

If the luminance of light emitted from an organic material is raised infuture, the light emitting device can be used in a front or rearprojector by magnifying and projecting outputted light that containsimage information with a lens etc.

Electric apparatuses as those given in the above-mentioned now displayinformation distributed through Internet, CATV (cable television), andother electronic communication lines, animation information, inparticular, with increasing frequency. Organic materials have very fastresponse speed and therefore light emitting devices are preferable modesfor displaying animated images.

When displaying information on a light emitting device, it is preferredto allow as small number of pixels as possible to emit light because thelight emitting device consumes more power as the number of emittingpixels is increased. Therefore, if a light emitting device is used in adisplay unit that mainly displays text information such as a portableinformation terminal, particularly a cellular phone or an audioreplaying device, the display device is preferably driven so that pixelsemitting light form text information white pixels that are not emittinglight form the background on the screen.

As described above, the light emitting device manufactured in accordancewith the present invention has a very wide application range and isapplicable to electric appliances of every field. The electricappliances of this embodiment can employ as their display units thelight emitting devices manufactured in Embodiments 1 through 8.

The present invention can provide a light emitting device having alow-resistant conductive film by forming an electrode from a transparentconductive film, a transparent conductive resin, and conductors.

The transparent conductive film and the transparent conductive resin aretransparent and have conductivity, and an opening is provided betweenadjacent conductors. Therefore light emitted from the organic compoundlayer can reach outside through the opening. This allows the organiccompound layer to emit light upward. A light-shielding material may beemployed for the lower electrode.

The present invention employs a sealing method in which the contactbetween the organic compound layer and oxygen or moisture is avoided byforming the transparent conductive resin between the transparentconductive film and the conductors. Accordingly there is no need toprovide a space filled with inert gas, making it possible to reduce thethickness of the light emitting device greatly.

1. A light emitting device comprising: a plurality of light emittingelements, each of the plurality of light emitting elements comprising: afirst electrode; a second electrode; an organic compound layerinterposed between the first and second electrodes; one of the first andsecond electrodes comprising: a transparent conductive film; atransparent conductive resin formed on the transparent conductive film;a plurality of conductors formed on the transparent conductive resin. 2.A light emitting device comprising: a plurality of light emittingelements, each of the plurality of light emitting elements comprising: afirst electrode; a second electrode; an organic compound layerinterposed between the first and second electrodes; one of the first andsecond electrodes comprising: a transparent conductive film; atransparent conductive resin formed on the transparent conductive film;a plurality of conductors formed on the transparent conductive resin,wherein a partition wall is formed between adjacent light emittingelements.
 3. A light emitting device comprising: a plurality of lightemitting elements, each of the plurality of light emitting elementscomprising: at least a thin film transistor; an insulating film over atleast one of a gate electrode of the thin film transistor, a gate wiringconnected to the thin film transistor, a source wiring connected to thethin film transistor, a drain wiring connected to the thin filmtransistor, and a current supply wiring connected to the thin filmtransistor; a transparent conductive film; a transparent conductiveresin formed on the transparent conductive film; a plurality ofconductors formed on the transparent conductive resin.
 4. A deviceaccording to claim 1, wherein a seal pattern is formed outside each ofthe light emitting elements, and wherein at least an opening is formedin the seal pattern.
 5. A device according to claim 1, wherein at leastan opening is formed between adjacent conductors.
 6. A device accordingto claim 1, wherein at least an opening is formed between adjacentconductors, and wherein a light emitted from the organic compound layerreaches outside through the opening.
 7. A device according to claim 1,wherein each of the plurality of conductors has a width in a range of0.5 to 5 μm.
 8. A device according to claim 5, wherein the opening has awidth in a range of 10 to 100 μm.
 9. A device according to claim 5,wherein a width of the opening is 5 to 15 times of a width of each ofthe plurality of conductors.
 10. A device according to claim 1, whereinthe light emitting device is in combination with an electric apparatus,wherein the electric apparatus is one selected from the group consistingof a display device, a digital still camera, a notebook computer, amobile computer a portable image reproducing device provided with arecording medium, a goggle-type display, a video camera, a portableimage taking display apparatus.
 11. A method of manufacturing a lightemitting device, said method comprising: forming an organic compoundlayer over a first surface of a substrate; forming at least a conductorover a second surface of a cover member; opposing the first surface ofthe substrate and the second substrate; bonding the substrate and thecover member with a seal pattern.
 12. A method of manufacturing a lightemitting device, said method comprising: forming an organic compoundlayer over a first surface of a substrate; forming at least a conductorover a second surface of a cover member; forming a seal pattern alongend portions of the cover member; forming a transparent conductive resininside the seal pattern over the cover member; opposing the firstsurface of the substrate and the second surface of the cover member;bonding the substrate and the cover member with the seal pattern.
 13. Amethod of manufacturing a light emitting device, said method comprising:forming an organic compound layer over a first surface of a substrate;forming a seal pattern along end portions of the substrate; forming atransparent conductive resin inside the seal pattern over the substrate;forming at least a conductor over a second surface of a cover member;opposing the first surface of the substrate and the second surface ofthe cover member; bonding the substrate and the cover member with theseal pattern.
 14. A method of manufacturing a light emitting device,said method comprising: forming an organic compound layer over a firstsurface of a substrate; forming at least a conductor over a secondsurface of a cover member; forming a seal pattern along end portions ofthe cover member; opposing the first surface of the substrate and thesecond substrate; bonding the substrate and the cover member with theseal pattern; injecting a transparent organic resin through an openingformed in the seal pattern.
 15. A method of manufacturing a lightemitting device, said method comprising: forming an organic compoundlayer over a first surface of a substrate; forming at least a conductorover a second surface of a cover member; forming a seal pattern alongend portions of the substrate; opposing the first surface of thesubstrate and the second substrate; bonding the substrate and the covermember with the seal pattern; injecting a transparent organic resinthrough an opening formed in the seal pattern.
 16. A method according toclaim 11, wherein the light emitting device is in combination with anelectric apparatus, wherein the electric apparatus is one selected fromthe group consisting of a display device, a digital still camera, anotebook computer, a mobile computer, a portable image reproducingdevice provided with a recording medium, a goggle-type display, a videocamera, a portable image taking display apparatus.
 17. A methodaccording to claim 12, wherein the light emitting device is incombination with an electric apparatus, wherein the electric apparatusis one selected from the group consisting of a display device, a digitalstill camera, a notebook computer, a mobile computer, a portable imagereproducing device provided with a recording medium, a goggle-typedisplay, a video camera, a portable image taking display apparatus. 18.A method according to claim 13, wherein the light emitting device is incombination with an electric apparatus, wherein the electric apparatusis one selected from the group consisting of a display device, a digitalstill camera, a notebook computer, a mobile computer, a portable imagereproducing device provided with a recording medium, a goggle-typedisplay, a video camera, a portable image taking display apparatus. 19.A method according to claim 14, wherein the light emitting device is incombination with an electric apparatus, wherein the electric apparatusis one selected from the group consisting of a display device, a digitalstill camera, a notebook computer, a mobile computer, a portable imagereproducing device provided with a recording medium, a goggle-typedisplay, a video camera, a portable image taking display apparatus. 20.A method according to claim 15, wherein the light emitting device is incombination with an electric apparatus, wherein the electric apparatusis one selected from the group consisting of a display device, a digitalstill camera, a notebook computer, a mobile computer, a portable imagereproducing device provided with a recording medium, a goggle-typedisplay, a video camera, a portable image taking display apparatus. 21.A device according to claim 6, wherein the opening has a width in arange of 10 to 100 μm.
 22. A device according to claim 6, wherein awidth of the opening is 5 to 15 times of a width of each of theplurality of conductors.
 23. A device according to claim 2, wherein aseal pattern is formed outside the light emitting element, and whereinat least an opening is formed in the seal pattern.
 24. A deviceaccording to claim 2, wherein at least an opening is formed betweenadjacent conductors.
 25. A device according to claim 2, wherein at leastan opening is formed between adjacent conductors, and wherein a lightemitted from the organic compound layer reaches outside through theopening.
 26. A device according to claim 2, wherein each of theplurality of conductors has a width in a range of 0.5 to 5 μm.
 27. Adevice according to claim 24, wherein the opening has a width in a rangeof 10 to 100 μm.
 28. A device according to claim 25, wherein the openinghas a width in a range of 10 to 100 μm.
 29. A device according to claim24, wherein a width of the opening is 5 to 15 times of a width of eachof the plurality of conductors.
 30. A device according to claim 25,wherein a width of the opening is 5 to 15 times of a width of each ofthe plurality of conductors.
 31. A device according to claim 2, whereinthe light emitting device is in combination with an electric apparatus,wherein the electric apparatus is one selected from the group consistingof a display device, a digital still camera, a notebook computer, amobile computer, a portable image reproducing device provided with arecording medium, a goggle-type display, a video camera, a portableimage taking display apparatus.
 32. A device according to claim 3,wherein at least an opening is formed between adjacent conductors.
 33. Adevice according to claim 3, wherein at least an opening is formedbetween adjacent conductors, and wherein a light emitted from theorganic compound layer reaches outside through the opening.
 34. A deviceaccording to claim 3, wherein each of the plurality of conductors has awidth in a range of 0.5 to 5 μm.
 35. A device according to claim 32,wherein the opening has a width in a range of 10 to 100 μm.
 36. A deviceaccording to claim 33, wherein the opening has a width in a range of 10to 100 μm.
 37. A device according to claim 32, wherein a width of theopening is 5 to 15 times of a width of each of the plurality ofconductors.
 38. A device according to claim 33, wherein a width of theopening is 5 to 15 times of a width of each of the plurality ofconductors.
 39. A device according to claim 3, wherein the lightemitting device is in combination with an electric apparatus, whereinthe electric apparatus is one selected from the group consisting of adisplay device, a digital still camera, a notebook computer, a mobilecomputer, a portable image reproducing device provided with a recordingmedium, a goggle-type display, a video camera, a portable image takingdisplay apparatus.